Engineering masterclass sees cables drilled underneath railway - while trains run above
A masterclass in engineering saw a new high-voltage cable route installed underneath the rail and tram network, as part of a power upgrade in South London.
The £7 million cable replacement project from Sydenham Park to Churchfields installed nine kilometres of brand new 33,000-volt cables underground to upgrade critical electricity infrastructure in the area and ensure reliable power supplies for the community.
A horizontal directional drill (HDD) was used to pave the way for the most significant part of the route, underneath the railway and tram lines at Avenue Road Station.
It carved out a 50-centimetre tunnel to house cables that were pulled underneath the railway line while rail and tram services continued above.
The team on site used horizontal directional drilling, a specialist technique that allows cables to be installed safely beneath railway infrastructure without the need for major roadworks. By using an underground bore, the method helps reduce disruption for passengers, road users and the local community.
The new cross-linked polyethylene solid cables will upgrade the local electricity network, ensuring safe and reliable electricity for thousands of customers.
The project also supports UK Power Networks’ commitment to environmental stewardship, aligning with the Groundwater Regulations 2009 and industry standards.
In addition to the cable replacement, the project includes the installation of spare ducts to future-proof the network and facilitate further upgrades.
The initiative is closely coordinated with the £20 million Beddington–Sydenham 132,000-volt project, maximising efficiency and minimising disruption for residents and businesses.
UK Power Networks project manager, Jason Callaghan, said: “We’re installing modern cross-linked polyethylene cables, futureproofing the network and delivering a more resilient supply for our customers.
“The main driver for the project is to upgrade the cable circuits between Sydenham Park and Churchfields, it’s a major step forward for local network reliability. There has been close liaison with Transport for London, Network Rail and the council, to carry out the HDD effectively.”
Portfolio manager, Claire Sheridan, said: “We’re investing around £30 million to replace 132,000-volt and 33,000-volt cables between Sydenham Park to Churchfields and Beddington to Sydenham. It’s an extremely busy route with lots of other utilities’ equipment underground, and above ground we are squeezed between residential streets, tramlines and an active railway.
“The HDD is a complex engineering operation that keeps the trains running and the streets open while the works take place. First we drill a small pilot hole, then we progressively widen it four times in order to achieve the correct diameter to pull the ducts through. We pulled the ducts through beneath the railway, keeping a safe distance from homes and track.”
Fintan McCusker at McCormack Drilling said: “This was a challenging project given the tight suburban location, railway infrastructure, and utilities to be negotiated by HDD. Our team worked closely with UK Power Networks and Clancy to develop a workable solution to the many engineering challenges at this location. It required meticulous attention to detail right through from feasibility, design, planning through to installation.”
Richard Fisher, client delivery lead within Savills Utilities and Infrastructure team, said: "Working alongside UK Power Networks Major Projects Consents and Stakeholder Engagement teams in a complex urban environment, Savills Land Assembly and Building & Project Consultancy teams provided a suite of services to support the successful delivery of this project. Close coordination between teams across UK Power Networks, Savills, and delivery contractors was essential in securing the necessary consents and maintaining relationships with stakeholders throughout the project."
Published: 12/08/2026
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The £7 million cable replacement project from Sydenham Park to Churchfields installed nine kilometres of brand new 33,000-volt cables underground to upgrade critical electricity infrastructure in the area and ensure reliable power supplies for the community.
A horizontal directional drill (HDD) was used to pave the way for the most significant part of the route, underneath the railway and tram lines at Avenue Road Station.
It carved out a 50-centimetre tunnel to house cables that were pulled underneath the railway line while rail and tram services continued above.
The team on site used horizontal directional drilling, a specialist technique that allows cables to be installed safely beneath railway infrastructure without the need for major roadworks. By using an underground bore, the method helps reduce disruption for passengers, road users and the local community.
The new cross-linked polyethylene solid cables will upgrade the local electricity network, ensuring safe and reliable electricity for thousands of customers.
The project also supports UK Power Networks’ commitment to environmental stewardship, aligning with the Groundwater Regulations 2009 and industry standards.
In addition to the cable replacement, the project includes the installation of spare ducts to future-proof the network and facilitate further upgrades.
The initiative is closely coordinated with the £20 million Beddington–Sydenham 132,000-volt project, maximising efficiency and minimising disruption for residents and businesses.
UK Power Networks project manager, Jason Callaghan, said: “We’re installing modern cross-linked polyethylene cables, futureproofing the network and delivering a more resilient supply for our customers.
“The main driver for the project is to upgrade the cable circuits between Sydenham Park and Churchfields, it’s a major step forward for local network reliability. There has been close liaison with Transport for London, Network Rail and the council, to carry out the HDD effectively.”
Portfolio manager, Claire Sheridan, said: “We’re investing around £30 million to replace 132,000-volt and 33,000-volt cables between Sydenham Park to Churchfields and Beddington to Sydenham. It’s an extremely busy route with lots of other utilities’ equipment underground, and above ground we are squeezed between residential streets, tramlines and an active railway.
“The HDD is a complex engineering operation that keeps the trains running and the streets open while the works take place. First we drill a small pilot hole, then we progressively widen it four times in order to achieve the correct diameter to pull the ducts through. We pulled the ducts through beneath the railway, keeping a safe distance from homes and track.”
Fintan McCusker at McCormack Drilling said: “This was a challenging project given the tight suburban location, railway infrastructure, and utilities to be negotiated by HDD. Our team worked closely with UK Power Networks and Clancy to develop a workable solution to the many engineering challenges at this location. It required meticulous attention to detail right through from feasibility, design, planning through to installation.”
Richard Fisher, client delivery lead within Savills Utilities and Infrastructure team, said: "Working alongside UK Power Networks Major Projects Consents and Stakeholder Engagement teams in a complex urban environment, Savills Land Assembly and Building & Project Consultancy teams provided a suite of services to support the successful delivery of this project. Close coordination between teams across UK Power Networks, Savills, and delivery contractors was essential in securing the necessary consents and maintaining relationships with stakeholders throughout the project."
Published: 12/08/2026
Back to news